Rule broken by English knight in branch of church (12)
I believe the answer is:
denomination
'church' is the definition.
(thesaurus)
'rule broken by english knight in branch' is the wordplay.
I cannot quite see how this works, but
'by' could be 'at' and 'at' is present in the answer.
'english' could be 'e' (abbreviation as in OED) and 'e' is found in the answer.
'knight' could be 'n' (chess abbreviation) and 'n' is found within the answer.
'rule' could be 'dominion' (synonyms) and 'dominion' is located in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for denomination that I've seen before include "Face value of a banknote, coin or postage stamp" , "sect" , "Religious group - grade in series of designated values" , "Note's face value" , "Value of postage stamp; branch of religion" .)